Oil heater



FIG. 1 is a front elevational view of the oil heater showing our newdesign;

FIG. 2 is a rear elevational view thereof;

FIG. 3 is a top plan view thereof;

FIG. 4 is a bottom plan view thereof;

FIG. 5 is a right side elevational view thereof; and

FIG. 6 is a left side elevational view thereof.

The ornamental design for an oil heater, as shown and described.